36 x 2 + 36 x 5 + 36 x 3

               = 36 x ( 2 + 3 + 5 )

               = 36 x 10

               = 360

Lấy máy tính bấm  nhé 

      \(36^2+24^2+36.48\)

\(=36^2+2.36.24+24^2\)

\(=\left(36+24\right)^2=60^2=3600\)

a) 1+2+3+...+99+100

giải

Từ 1 đến 100  có 100 số.Như vậy,số cặp số là:

100:2=50(cặp)

Mỗi cặp số có tổng bằng:

1+100(2+99)(3+98)...=11

Kết quả của phép tính là:

101x50=5050

Đáp số:5050

1+2+...+100=(1+100).100/2=5150

Bài 1 :

a) 37581 - 9999 = 37581 - 10000 - 1 = 27581 - 1 = 27580

k cho mình nha bạn ! 

a)37581-9999=37581-(9999+1-1)=37581-(10000+1)=37581-10000-1=27581+1=27582

36/9 : 5/14 + 36/9 : 2/14

= 36/9 : ( 5/14 + 2/14) 

= 36/9 : 2/7

=252/18

   có j sai sót mong em bỏ qua nhé- tại chị học qua lâu rùi nên ko nhớ lăm!!!!!:3

sorry pé nhá

  36/9 : ( 5/14 + 2/14 )

= 36/9 : 7/14

( 36/9 = 4)

=4: 7/14

=56/7 

 nhá hồi nãy chị làm nhầm:)

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)

\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{99.100}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{99}-\frac{1}{100}\)

\(=1-\frac{1}{100}=\frac{99}{100}\)

Mình chỉnh lại đề B nha:

\(B=\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+...+\frac{1}{9999}\)

\(=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+...+\frac{1}{99.101}\)

\(=\frac{1}{2}\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{101}\right)\)

\(=\frac{1}{2}\left(1-\frac{1}{101}\right)\)

\(=\frac{1}{2}.\frac{100}{101}=\frac{50}{101}\)

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)

\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)

\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(A=1-\frac{1}{100}\)

\(A=\frac{99}{100}\)

`5/2 - 2/3 + 5/4`

`= 30/12 - 8/12 + 15/12`

`= (30-8+15)/12`

`= 37/12`

`----`

`20/12 + 36/18 -21/28`

`= 5/3 + 2-3/4`

`= 20/12 + 24/12 -9/12`

`= 35/12`

`5/2-2/3+5/4`

`=30/12-8/12+15/12`

`=37/12`

`20/12+36/18-21/28`

`=5/3+2-3/4`

`=20/12+24/12-9/12`

`=35/12`

\(2\frac{1}{2}+3\frac{1}{18}+7\frac{5}{36}\)

\(=\frac{5}{2}+\frac{55}{18}+\frac{257}{36}\)

\(=\frac{90}{36}+\frac{110}{36}+\frac{257}{36}\)

\(=\frac{90+110+257}{36}=\frac{457}{36}\)

\(2\frac{1}{2}+3\frac{1}{18}+7\frac{5}{36}\)

\(=\left(2+3+7\right)\left(\frac{1}{2}+\frac{1}{18}+\frac{5}{36}\right)\)

\(=12\left(\frac{1}{2}+\frac{1}{18}+\frac{5}{36}\right)\)

\(=12\frac{25}{36}=\frac{457}{36}\)